Rafael Nadal has dismissed concerns over his form, insisting he is in 'good shape' ahead of the Australian Open.

The 22-time Grand Slam winner battled chronic foot problem and two abdominal tears at the back end of last season and started the new year in underwhelming fashion. 

The Spaniard failed to win both of his singles matches at the United Cup, losing to Britain's Cameron Norrie and Australia's Alex De Minaur despite winning the opening set in both occasions.

Speaking on commentary for Nine, tennis great Jim Courier noted Nadal served wider than usual against De Minaur and suggested the subtle change indicated the 36-year-old was yet to completely recover from his abdominal injury.

Nadal, however, insisted preparation ahead of the Australian Open had gone smoothly but conceded he would have to back up his claims on the court. 

'It's true that the last couple of tournaments I wasn't able to play my standards and here at the beginning of the season I lost two matches in Sydney, but honestly, I am not unhappy with the preparation,' he told reporters on Tuesday.

'I think I'm in good shape. You need to demonstrate that in matches […] but I'm confident that if I am able to have this last week of positive practice, why not?'

Nadal and his wife, Xisca Perello, welcomed a baby boy named Rafael Jr in October, but there were complications with the pregnancy and she was required to spend time in hospital in September.

However, the Spaniard opted to head to New York for the US Open, leaving the doctors to monitor his wife in Mallorca while he looked to add to his haul of Grand Slams.

Speaking in Sydney last week, the 36-year-old revealed his wife had encouraged him to compete in the US Open and then head to London to feature in Roger Federer's emotional tennis farewell.

The two-time Australian Open winner insisted becoming a father had not had a negative impact on his performances, but conceded he had to adapt around his new reality.

'It's about adapting to this new part of my life in all ways,' he said.

'You need a little bit more organisation than before without a doubt. But it's the first time that happens in my life.

'So I need some time to adjust to all the things that are going to help me to stay the same as before, but I think I have all the things around me that help me to keep going without problems.'